public void GetFieldIndex_ShouldFind()
{
var comp = new ExpressionCompiler <Action>();
var fieldFi = typeof(Obj).GetField("Field");
var objVar = comp.Variable <Obj>("obj");
var realIndex = comp.Field(objVar, fieldFi);
var foundIndex = comp.GetFieldIndex(fieldFi);
Assert.Equal(realIndex, foundIndex);
}